Optimising RF connector selection: technical considerations for signal integrity

Operating across frequencies from a few MHz to several GHz, RF connectors are essential in applications like telecommunications, satellite communications and defence systems. Whether you’re designing a new circuit or upgrading an existing one, connector choice significantly impacts your system’s functionality and durability. Here Federico Sangregorio, EMEA RF Engineer at connector specialist PEI-Genesis, explores the key considerations for effective RF connector selection.

RF connectors are specialised connectors designed to operate at radio frequencies in the multi-megahertz range. They are used to connect coaxial cables, which are essential for transmitting signals in various RF applications, including broadcasting, military and medical devices. The primary function of RF connectors is to ensure a secure, low-loss connection between the components in an RF system. But with so many types and variations available, how do you choose the right one?

Frequency range

One of the first considerations when selecting an RF connector is the frequency range of your application. RF connectors are designed to operate effectively within specific frequency ranges.

For applications operating below 1 GHz, such as traditional broadcast radio (FM/AM), television transmission and some early-generation cellular networks, the frequency demands are relatively low. In these scenarios, connectors like the Bayonet Neill–Concelman (BNC) and F-type connectors are commonly used.

Moving into higher frequency ranges, such as those used in Wi-Fi (2.4 and 5 GHz bands), GPS systems (1.575 and 1.227 GHz) and modern cellular networks (up to 6 GHz), the requirements for connectors become more stringent. SMA (Sub-Miniature version A) connectors are a popular choice for these mid-frequency applications due to their compact size, reliable performance and ability to handle frequencies up to 18 GHz. SMA connectors are commonly used in Wi-Fi routers, cellular base stations and GPS devices, where they provide low insertion loss and high return loss, ensuring that the signal maintains its integrity across the connection.

In high-frequency applications like satellite and 5G communications, which exceed 10 GHz, connectors must meet demanding requirements. The 2.92 mm (K) and SMP connectors are ideal for these uses, with the 2.92 mm connector supporting up to 40 GHz, making it essential for maintaining signal integrity in microwave systems and satellite communications.

For the most demanding applications, such as millimetre-wave communications, automotive radar and certain scientific instruments, the frequency range can extend above 40 GHz. In these cases, specialised connectors like the 1.85 mm (V connectors) and 1 mm connectors are used. The 1.85 mm connector supports frequencies up to 67 GHz and is often employed in high-frequency testing and measurement systems, where precision and minimal signal degradation are critical.

Choosing a RF connector that matches or exceeds your frequency requirements is essential to maintain signal integrity and minimise losses. A mismatch in the frequency range can lead to signal attenuation, reflection and even complete signal loss.

Power handling

Another crucial factor in selecting RF connectors is power handling, particularly in applications where the system must transmit significant amounts of power. The power rating of an RF connector indicates the maximum amount of power it can safely carry without compromising performance, leading to issues such as overheating, signal distortion or even physical damage to the connector.

In low-power applications, such as consumer wireless devices or small-scale networking equipment, the power requirements are generally modest, often in the range of milliwatts to a few watts. Connectors like the SMA and Micro-Miniature Coaxial (MMCX) are commonly used in these scenarios. The SMA connector, for instance, can typically handle power levels up to 500 W at lower frequencies, making it suitable for many mid-power applications in networking and wireless communications.

On the other hand, high-power applications, such as in radar systems, military communications and large-scale broadcasting, demand connectors that can handle power levels in the kilowatt range. The 7/16 DIN connector is a prime example, specifically designed to handle high-power transmissions with minimal loss and high resistance to passive intermodulation (PIM). These connectors can handle power levels exceeding 5000 W at lower frequencies and are commonly used in broadcast towers, high-power RF amplifiers and base stations for cellular networks.

Environmental considerations

Environmental factors, such as humidity, temperature and exposure to corrosive substances, can significantly impact the performance of RF connectors. For applications in extreme conditions, such as military or aerospace, it’s crucial to select connectors with appropriate environmental sealing and protection. IP-rated connectors, for example, provide ingress protection against dust and water, ensuring reliable performance in challenging environments. Similarly, connectors with Teflon or other specialised insulators can withstand high temperatures, making them suitable for use in engines or other high-heat areas.

Selecting the right RF connector is a nuanced process that requires careful consideration of various factors, including frequency range, power handling and environmental resilience. Each application has its unique requirements, and the ideal connector will be one that balances all these factors to deliver optimal performance.

To find out about the extensive range of RF connectors offered by PEI-Genesis, visit www.peigenesis.com.

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